RESEARCH ARTICLE
The expression and function of KCNQ potassium channels in human chorionic plate arteries from women with normal pregnancies and pre-eclampsia Xiaohong Wei1☯, Yujiao Zhang1☯, Benlan Yin1, Jing Wen2, Jun Cheng2, Xiaodong Fu1*
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1 Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China, 2 Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China ☯ These authors contributed equally to this work. *
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Abstract OPEN ACCESS Citation: Wei X, Zhang Y, Yin B, Wen J, Cheng J, Fu X (2018) The expression and function of KCNQ potassium channels in human chorionic plate arteries from women with normal pregnancies and pre-eclampsia. PLoS ONE 13(3): e0192122. https://doi.org/10.1371/journal.pone.0192122 Editor: Bernard Attali, Tel Aviv University Sackler Faculty of Medicine, ISRAEL Received: February 14, 2017 Accepted: January 18, 2018 Published: March 26, 2018 Copyright: © 2018 Wei et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: This study was supported by Sichuan Provincial Science and Technology Department, [2014]no.10, URL http://www.scst.gov.cn/. XDF is the author who received the funding. Contributions of the author XDF include conceptualization, formal analysis, resources, supervision, and writing review & editing.
Pre-eclampsia is associated with altered maternal and placental vascular reactivity. Kv7 channels (encoded by KCNQ 1–5 genes) are a potential contributor to the regulation of vascular tone in CPAs (chorionic plate arteries) during normal pregnancy. The aim of this study is to establish the expression profile of KCNQ subunits in CPAs taken from women with preeclampsia or normotensive women and to examine the functional relevance of the Kv7 channels on an altered expression profile of KCNQ subunits. The effects of Kv7 channel modulators on CPAs were investigated by tension measurement. Quantitative PCR experiments were used to analyze the expression of KCNQ genes. Western blotting and immunofluorescence were both used to analyze the protein expression of Kv7 channels. Finally, in CPAs from normotensive women, the Kv7 channel blocker XE991 increased arterial basal tone and U46619induced contraction, and pre-contracted CPAs (10−7 M U46619) exhibited significant relaxation following treatment with Retigabine(Kv7.2–7.5 activator) and BMS-204352(Kv7.2–7.5 activator). However, ICA-27243(selective KCNQ2 and KCNQ3 activator) and ML277(selective KV7.1 activator) had no significant effect on tension in the pre-contracted CPAs. Conversely, compared with CPAs from normotensive women, the effects of XE991 on basal tone and agonist (U46619)-induced contractions in CPAs from women with preeclampsia were markedly attenuated. Moreover, the relaxation effects of Retigabine and BMS-204352 on precontracted CPA vessels from women with pre-eclampsia were also markedly down-regulated. Interestingly, the relaxation ability of ICA-27243 in pre-contracted CPA vessels in women with pre-eclampsia was enhanced. The mRNA of KCNQ3 was specifically up-regulated, whereas those for KCNQ4 and KCNQ5 were down-regulated in CPAs from women with pre-eclampsia compared with those in normotensive women. Similar observations were found in a subsequent analysis of protein expression of KCNQ genes 3–5. Thus, down-regulated Kv7 channel function in tension regulation of CPAs in women with pre-eclampsia could be associated with considerably altered expression profiles of Kv7 subunits.
PLOS ONE | https://doi.org/10.1371/journal.pone.0192122 March 26, 2018
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KCNQ potassium channels in human chorionic plate arteries
Competing interests: The authors have declared that no competing interests exist.
Introduction Pre-eclampsia is currently the most common and significant complication in obstetrics, complicating 3–5% of all pregnancies [1]. Preeclampsia, hemorrhage and infection are the three leading causes contributing to maternal and perinatal morbidity and mortality worldwide [1– 2]. The essential clinical presentation of preeclampsia traditionally entails new-onset hypertension and proteinuria occurring after 20 weeks of gestation in a previously normotensive woman. However, maternal multiorgan dysfunction is also included in the manifestations of this disorder, according to the new definition [2–3]. This disorder is universally combined with fetal growth restriction and preterm delivery. Women with complicated preeclampsia and their neonates are at increased risk of hypertension, metabolic disorders, cardiovascular disease and cardiovascular death in their future lives [4–5]. The pathophysiology of preeclampsia is complex. Placental dysfunction and impaired remodeling of the spiral arteries are almost certainly contributors to this disease [6–8]. Reduced uteroplacental arterial flow and irregular placental perfusion result in hypoxia or reoxygenation episodes [9], which lead to placental oxidative stress and dysfunction [10] and subsequently a generalized hyper inflammatory state compared with normal pregnancy [11]. The excessive inflammatory response results in exaggerated endothelial activation and altered maternal and placental vascular reactivity [12]. The fetal-placental circulation mediates exchange of nutrients and waste products between the maternal and perinatal systems and thereby supplies adequate oxygen/nutrients for normal fetal development [13]. Chorionic plate arteries (CPAs) return deoxygenated blood from the fetus to the feto-maternal interface where gas/nutrient exchange occurs, playing a vital role in the fetal-placental circulation [13, 14]. The exaggerated endothelial activation and altered placental vascular reactivity of CPAs in women with pre-eclampsia increase vascular tone and reduce fetoplacental blood flow preceding onset of clinical manifestations such as fetal growth restriction and preterm [15]. It’s accepted that Potassium channels are the predominant mediators of modulation of smooth muscle contractility due to their decisive role in changes in cell membrane potential (Vm) [16,17]. The depolarization of vascular smooth muscle cells (VSMCs), resulting from inhibition of K+ channels, leads to a calcium (Ca2+) influx via L-type voltage-dependent Ca2+ channels and subsequent vasocontraction [18]. Several reviews over the past decades have implicated K+ channels in regulating excitation-contraction coupling of CPAs, including Kv, KATP, K2P and KCa channels [19]. Kv7 channels (encoded by KCNQ genes), subfamily of voltage-gated potassium channel complexes, have recently become a hot topic because of their important contributions to the regulation of contractility of VSMCs. The first report that Kv7 channels in VSMCs was in the mouse portal vein[20].Yeung and Greenwood implicated their important contribution to resting membrane voltage and smooth muscle excitability [21]. Kv7 channels were also shown to be expressed in numerous blood vessels, including pulmonary arteries, mesenteric arteries and coronary arteries of rats and mice, as well as in rat middle cerebral and basilar arteries, where they play an important role in the regulation of vascular reactivity [22–24]. The broad spectrum Kv7 blockers, linopirdine and XE991, cause vascular contraction of a number of blood vessels including the mesenteric, pulmonary and cerebral arteries, whereas the activator retigabine relaxes pre-constricted artery vessels [23–25]. Further observations have shown the expression and function of variable Kv7 channel isoforms in human visceral fat and mesenteric arteries [26]. More recently, CPAs were found to express Kv7 channels that constricted in response to linopirdine and were relaxed by the Kv7.2–5 specific activators flupirtine, Retigabine and S-1 in normotensive patients [27]. Considering their excitability-regulating abilities, Kv7 channels could be very promising new therapeutic targets
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KCNQ potassium channels in human chorionic plate arteries
for treatment of pre-eclampsia cases where compromised fetoplacental blood flow is apparent, but their pathophysiological role in these disorders has not yet been reported. Hence, the aim of this study was to extend previous work on Kv7 channels in CPAs by establishing the expression profiles of KCNQ subunits in CPAs taken from women with preeclampsia, as well as normotensive controls, and examining the functional relevance of the KCNQ channels on altered expression profiles.
Materials and methods This study was approved by the ethics committee of Luzhou Medical College, and written informed consents were obtained from all women prior to initiation of delivery. A total of 46 cases were recruited from May 2015 to May 2016 by either vaginal delivery or caesarean section, including 26 cases diagnosed with preeclampsia as the experimental group (pre-eclampsia, PE) and 20 cases with normotensive pregnancy serving as a control group (normotensive pregnancy, NP). The clinical characteristics of all participating cases were obtained, including maternal age, primipara, blood pressure, proteinuria, birth weight, gestational age at delivery (wk), number of deliveries < 37 wk (n [%]) and proportion of FGR [28] (Table 1). Cases of pre-eclampsia were admitted according to the American College of Obstetricians and Gynecologists’ (ACOG) guidelines [29–30]. All cases with complications of pregnancy (including cardiovascular disease, severe liver and kidney disease, immune system disease, endocrine disease, cancer, mental or cognitive disorders), obstetricalcomplications (gestational diabetes, multiple pregnancies, placental abruption and placenta previa) and other relevant medical histories (smoking, drinking, a history of drug use during pregnancy history, etc.) were excluded. Small tissue samples, approximately 2×2×2 cm3, were immediately taken from newly delivered placentas at a location midway between the root of the umbilical cord and the border of the placenta and placed into ice-cold normal Tyrode’s solution (in mM: 127 NaCl, 5.9 KCl, 1.2 MgCl2, 2.4 CaCl2, 12 Glucose, 10 HEPES; pH 7.4 with NaOH). Then, appropriately sized CPA branches were identified and surrounding connective tissues were removed under a stereoscopic microscope in ice-cold normal Tyrode’s solution.
Measurement of vascular tension in vitro The CPAs (lumen diameter ~300 μm) were cut into rings approximately 1.5–2 mm in length and mounted equidistantly in an organ chamber filled with 5 ml oxygenated (aerated with 95% O2, at 37˚C) normal Tyrode’s solution. As described previously, the initial resting tension Table 1. Clinical characteristics of all participating subjects. Parameter
Normal pregnancy(N = 20)
Preeclampsia(N = 26)
Matemal age
28.3±3.9
30.5±7.1
Primipara,n(%)
12(60)
10(38.5)
Maximum systolic(mm Hg)
114.5±9.8
170.8±15.3
Maximum diastolic(mm Hg)
75.9±9.0
110.9±143
Proteinuria, g/L(Maximum, minimum)
0.04(0.01, 0.23)
3.1 (0.14, 11.0)
Cesarean section, n (%)
3 (15)
11(42.3)
Gestational age at delivery
